Effect Of Pre-Fermentation Cold Soak On The Chemical And Sensory Qualities Of Aromatic White Wines PDF Download

Author: Diane Marie Schmitt
Publisher:
ISBN:
Category :
Languages : en
Pages : 141

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Book Description
The aroma profiles of Riesling, Gewürztraminer, and Traminette grapes are largely derived from monoterpenes found in grape pulp and skin. To optimize the extraction of monoterpenes and other volatile compounds, a winemaking technique called pre-fermentation cold soak (CS) is sometimes used. Unfortunately, CS may also allow for the extraction of undesirable bitter compounds, including monomeric phenolics. To address this concern, monomeric phenolic concentrations were measured in wines produced with varying CS durations. Among the compounds analyzed, (+)-catechin and ( - )-epicatechin were most affected by CS duration. Because total monomeric phenolic concentrations tended to increase with increasing CS duration, wine bitterness intensity was quantified by a trained panel. Sensory evaluation results, however, suggest that CS duration and bitterness intensity are not directly related. Following the CS study, detection thresholds of (+)-catechin and ( - )-epicatechin in model and commercial wines were determined in order to learn more about the contributions of these compounds to wine sensory characteristics. (+)-Catechin detection thresholds in model and commercial wines were 205 and 278 ppm, respectively. In contrast, the detection thresholds of ( - )epicatechin were not found for the concentrations tested which went up to 501ppm. Threshold testing was selected as a starting point to understand how individuals perceive these compounds at sub- and suprathreshold levels. CS and other processing conditions can lead to color compound extraction or must oxidation, resulting in darker colored wines and potentially increasing bitterness intensity. The presence of an association between darker white wine color and bitterness intensity was investigated by having a panel of wine professionals rate the bitterness of color-modified white wine samples. The results did not indicate that wine professionals associate darker white wine color with bitterness. A final study investigated the possibility of differentiating Riesling clones through the analysis of juice monomeric phenolic and tannin profiles. The results did not show significant differences in the monomeric phenolic and tannin profiles among the clones analyzed. However, preliminary sensory results suggest that wine professionals can differentiate among monoclonal Riesling wines. If true, it may be possible to differentiate among Riesling clones through the analysis of other volatile and non-volatile compounds.

Author: Conor McCaney
Publisher:
ISBN:
Category :
Languages : en
Pages :

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As the Pennsylvania wine industry continues to expand, a need for wine grape varieties capable of growing in the tough Northeastern United States climate, while producing consistent quality-driven wines is increasing. The Northeastern United States has always been a difficult place for European Vitis vinifera grape varieties to thrive, due to hotter and wetter conditions during the growing season. These conditions drive up fungal and disease pressure such as powdery mildew, downy mildew, and black rot, which V. vinifera has no natural immunity to. Additionally, the extreme cold during the winter season, makes the survival of V. vinifera varieties difficult, as they evolved around a Mediterranean climate. A potential aid to the Eastern United States wine industry has been the development of interspecific hybrid (Vitis ssp.) grape varietals, which are typically a cross of V. vinifera and non-Labrusca American varieties. These varieties have intended to capture the aromatic and flavor complexity and intensity characteristic of V. vinifera wines while retaining the cold tolerance, disease, and pest resistance found in American varieties. While these varieties have shown greater adaptation to the growing conditions of the Eastern United States, they have still lacked the phenolic development important to the perception of wine flavor and body as well as the aromatic intensity and complexity found in V. vinifera wines. With their lack of international renown, hybrid grapes have not gained full consumer acceptance and recognition. This study looked at adapting pre-fermentation novel maceration techniques to two white interspecific hybrids (V. ssp.), Cayuga, and Traminette, which are prevalent throughout the Eastern United States wine-growing regions. While pre-fermentation maceration techniques have been studied in white V. vinifera varieties previously, their mechanistic effects on interspecific hybrid (V. ssp.) white wine quality has not been thoroughly evaluated. Interspecific hybrid (V. ssp.) white wines have traditionally lacked aromatic and flavor complexity and intensity, while also being lower in phenolic content contributing to mouthfeel and a wine's ability to age. Previous studies on V. vinifera white varieties have reported significant beneficial effects on phenolic content, antioxidative activity, and desirable sensory attributes of finished wines from cryogenic maceration and cold soak techniques. This study looked at three different novel maceration techniques: rapid cryogenic, slow cryogenic, and cold soak. Rapid and slow cryogenic macerations in the initial study resulted in significant increases in total phenolic content as measured by Folin-Ciocalteu analysis, as well as a significant increase in antioxidant activity as measured by DPPH radical scavenging assay. Significant increases in browning at A420 and CIE-Lab tristimulus color parameters were observed in rapid and slow cryogenic juices. However, these changes were not carried over into the finished wines, although slow cryogenic maceration did produce a slightly more yellow and darker wine compared to rapid cryogenic maceration and the control. Both freezing rates significantly increased concentrations of gallic acid, catechin, and epicatechin in finished wines compared to the control wines. Aroma profiling by HS-SPME-GC/MS analysis revealed significant increases in the concentration of terpenes and esters in the cryogenic wines compared to the control. However, the types and amounts of aroma compounds enhanced by either freezing rate were dependent on variety. The second year of the study compared rapid cryogenic maceration using dry ice to a 6 hour cold soak. All processing was conducted in a strict anaerobic environment inside of single-use pharmaceutical fermentation bags. Significant increases in total phenolic content as measured by Folin-Ciocalteu analysis, as well as a significant increase in antioxidant activity as measured by DPPH radical scavenging assay, were observed in the cryogenic wines of both varieties compared to control wines. Additionally, increases were observed in both parameters for cold soak treatment. No significant differences were observed in either variety across treatments in terms of browning at A420 and CIE-Lab tristimulus color analysis. Analysis of gallic acid, catechin, and epicatechin by reverse-phase HPLC showed a significant increase in all three phenolics in both treatments compared to the control wines. Aroma analysis by HS-SPME-GC/MS showed significant increases in terpenes of the cryogenically treated wine compared to the control. Cold soak showed significant increases in esters in both varieties compared to control. Sensory analysis for Cayuga and Traminette wines showed significant differences in certain aroma and flavor references, taste references, visual and mouthfeel references. The cryogenic maceration treatment's ability to increase phenolic content and antioxidative content, while enhancing aromatic components compared to control wines, supports the technique's feasibility to potentially produce more stable and quality-driven white hybrid wines. Cold soak results also show the potential to achieve similar results to the cryogenic treatments utilizing a procedure that causes less cellular disruption and is less time-consuming. Cold soak may be a more variety-specific technique and also not exhibit the same magnitude in changes that cryogenic maceration achieves. In terms of applicability and feasibility to small scale wineries, as well as increases in quality and oxidative stability, using rapid cryogenic maceration with dry ice compared to liquid nitrogen or slow freezing may be the most viable option for implementing this technique.

Author: Ronald S. Jackson
Publisher: Academic Press
ISBN: 0128165375
Category : Technology & Engineering
Languages : en
Pages : 1032

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Book Description
Wine Science: Principles and Applications, Fifth Edition, delivers in-depth information and expertise in a single, science-focused volume, including all the complexities and nuances of creating a quality wine product. From variety, to the chemistry that transforms grape to fruit to wine, the book presents sections on the most important information regarding wine laws, authentication, the latest technology used in wine production, and expert-insights into the sensory appreciation of wine and its implications in health. This book is ideal for anyone seeking to understand the science that produces quality wines of every type. Presents thorough explanations of viticulture and winemaking principles from grape to taste bud Addresses historical developments in wine production, notably sparkling wines Provides techniques in grapevine breeding, notably CRISPR Compares production methods in a framework that provides insights into the advantages and disadvantages of each

Author: Fernanda Cosme
Publisher: BoD – Books on Demand
ISBN: 1839625759
Category : Science
Languages : en
Pages : 258

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Book Description
This book, written by experts, aims to provide a detailed overview of recent advances in oenology. Book chapters include the latest progress in the chemistry and biochemistry of winemaking, stabilisation, and ageing, covering the impact of phenolic compounds and their transformation products on wine sensory characteristics, emerging non-thermal technologies, fermentation with non-Saccharomyces yeasts, pathways involved in aroma compound synthesis, the effect of wood chips use on wine quality, the chemical changes occurring during Port wine ageing, sensory mechanisms of astringency, physicochemical wine instabilities and defects, and the role of cork stoppers in wine bottle ageing. It is highly recommended to academic researchers, practitioners in wine industries, as well as graduate and PhD students in oenology and food science.

Author: Andrew G. Reynolds
Publisher: Woodhead Publishing
ISBN: 008102066X
Category : Technology & Engineering
Languages : en
Pages : 890

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Book Description
Managing Wine Quality, Volume 2: Oenology and Wine Quality, Second Edition, brings together authoritative contributions from experts across the world's winemaking regions who cover yeasts, fermentation, enzymes, and stabilization, amongst other topics. A new chapter covers, in detail, extraction technologies and wine quality. Other sections cover the management of wine sensory quality, with new chapters covering the management of fortified wines, of Botrytized wines, and of wines produced from dried grapes. In addition, an updated section on insect taints in wine has been widened to cover all insects. With a focus on recent studies, advanced methods, and a look to future technologies, this fully updated edition is an essential reference for anyone involved in viticulture and oenology who wants to explore new methods, understand different approaches, and refine existing practices. - Reviews our current understanding of yeast and fermentation management, as well as the effects of aging on wine quality - Details alternatives to cork in bottle closing and the latest developments in the stabilization and clarification of wines - Includes new chapters covering extraction technologies for wine quality and on managing the quality of a wide range of wine types, including fortified and Botryized wines - Provides extensively expanded coverage of insect taints and their effects on wine quality

Author: Eugenio Cristian Lira Miranda
Publisher:
ISBN:
Category :
Languages : en
Pages : 121

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Book Description
This thesis shows the results obtained from adding bentonite at different stages of the alcoholic fermentation in protein stability and reducing the bentonite required to reach stability. Results reflect the effect of this practice on alcoholic fermentation, chemical composition of wines, protein content and profile, aromatic profile and foam quality. The study was carried at pilot and industrial scale, with several grape varieties, in different geographical areas and during three vintages. The advantage of using bentonite during alcoholic fermentation was established, especially in moderate doses, making the addition from the middle of fermentation, obtaining more stable wines with less bentonite. Wines that were stabilized by bentonite treatment during fermentation were the best sensorial evaluated. Reproducibility between scales was confirmed for almost every parameter checked. Protein fractions and bentonite stabilizing dose for the different white wines was also identified and correlated. A commonly used technique was improved, achieving better quality wines.

Author: Antonio Morata
Publisher: BoD – Books on Demand
ISBN: 1789846129
Category : Technology & Engineering
Languages : en
Pages : 298

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Book Description
Advances in Grape and Wine Biotechnology is a collection of fifteen chapters that addresses different issues related to the technological and biotechnological management of vineyards and winemaking. It focuses on recent advances in the field of viticulture with interesting topics such as the development of a microvine model for research purposes, the mechanisms of cultivar adaptation and evolution in a climate change scenario, and the consequences of vine water deficit on yield components. Other topics include the metabolic profiling of different Saccharomyces and non-Saccharomyces yeast species and their contribution in modulating the sensory quality of wines produced in warm regions, the use of new natural and sustainable fining agents, and available physical methods to reduce alcohol content. This volume will be of great interest to researchers and vine or wine professionals.

Author: Anthony Sereni
Publisher:
ISBN:
Category : Chardonnay (Wine)
Languages : en
Pages : 102

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Book Description
Mouthfeel is one of the most important quality parameters of Chardonnay wines. Malolactic fermentation (MLF) is an important process in wine production, and influential to wine mouthfeel, with the reduction in acidity being particularly important for cool climate wines that generally have higher acidity such as Chardonnay. MLF is typically induced by the addition of Oenococcus oeni after the completion of the alcoholic fermentation (AF) but can occur concurrent with AF by inoculating O. oeni simultaneously with the fermentative yeast Saccharomyces cerevisiae. We investigated the effect of MLF inoculation timing as well as the temperature of MLF and the presence of the non-Saccharomyces yeast Torulaspora delbrueckii on Chardonnay wine mouthfeel. Chardonnay wines were produced in 2014 with AF and MLF inoculated for simultaneous or sequential fermentations, and temperatures 15 and 21°C, with or without the addition of T. delbrueckii. Mouthfeel attributes of the wines produced were assessed by a winemaker panel, using Napping® and Ultra-flash profiling. Significant differences in mouthfeel perception were found based on timing and inoculation conditions, as well as between temperatures. Treatment type and temperature also effected the chemical composition of finished wines. Additionally, there are many interactions that occur between taste and aroma that may impact mouthfeel perception. This led us to investigate whether the aroma fraction of Chardonnay wine should be considered when investigating relationships between chemical composition and sensory perception of mouthfeel. Chardonnay wines were determined to have mouthfeel differences by altering the fermentation temperature of the alcoholic and malolactic fermentation as well as the timing of MLF and the presence of a non-Saccharomyces yeast during AF. Napping® and Ultra-flash-profiling were conducted using a panel of white winemakers. Each procedure was conducted twice: once with retro-nasal aroma and once without retronasal aroma. Napping® results showed that retronasal aroma impacted mouthfeel perception. Ultra-flash profiling displayed similar descriptive terms used with and without retronasal aroma, but terms were not consistently used for the same wine treatments with and without retronasal aroma. It is unclear if these differences are due to interactions or due to associated learning. These results suggest that for some mouthfeel terms the volatile fraction is playing a role and to establish relationships with chemical composition and mouthfeel perception it is important to consider both the volatile and nonvolatile wine fractions. We then investigated the impact of pre-fermentation juice treatments on mouthfeel characteristics of Chardonnay wine. Chardonnay grapes were harvested from Oregon State University’s vineyard in September, 2015. After destemming and pressing the juice was subjected to various treatments. These treatments included high, medium, and low turbidity level, as well as hyper-oxidation, two-hour skin contact, and two-hour skin contact + hyper-oxidation. All treatments went through alcoholic and malolactic fermentations. Total phenolics and hydroxycinnamic acids differed between skin contact and hyper-oxidation treatments. Wines that underwent hyper-oxidation contained the lowest total phenolics. Hyper-oxidation following skin contact reduced total phenolics but retained more than the hyper-oxidation treatment. Sensory analysis using citation by frequency procedure showed that all treatments modified the mouthfeel of finished wines. However, chemical analysis did not fully elucidate the cause of these differences. Pre-fermentation juice treatments can be utilized to develop stylistic differences in finished Chardonnay wine. The combined findings of this research demonstrate the usefulness of various enological practices to influence the sensory qualities of a Chardonnay wine, as well as emphasizing the importance of retro-nasal aroma’s influence on the mouthfeel experience of Chardonnay wine.

Author: Katie Jane Parish
Publisher:
ISBN:
Category : Fining (Wine making)
Languages : en
Pages : 268

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Book Description
Fining is a common practice used in the wine industry which assists with clarification and/or provides corrective treatment for the aroma, taste or aftertaste of a juice or wine. During this thesis project the fining agents activated carbon (AC), gelatin (G), gelatin with silicon dioxide (GSi), polyvinylpolypyrrolidone (PVPP), and a mixed agent consisting of bentonite, PVPP, and isinglass (M) where investigated for their ability to influence the concentration of several aroma compounds in Marlborough Sauvignon blanc. Sensory trials were also conducted to investigate if any chemical changes impact the sensory aspect of the wines. Although both free run and press fraction juice fining was considered, a stronger emphasis was placed on the production of press fraction wines. The focus of this thesis was conceived in direct collaboration with a winery which noted anecdotally that press fraction juices require severe fining regimes thought to be due to the extended skin contact and oxygen exposure they undergo. Therefore, the project set out to explore if pre-fermentation juice fining could modulate aroma compounds present in Marlborough Sauvignon blanc press fraction wines. The first fining trial conducted was to survey the potential for the chosen commercially available agents (AC, G, PVPP, and M) to induce a change in the aroma chemistry of the experimental wines. Both free run and press fraction juices of two vineyards (Awatere valley and Wairau valley) were fined and the resulting wines analysed. Results showed that several aroma compounds may be influenced by prefermentation fining. For instance, there was a significant (p 0.05) reduction in linalool and hexan-1-ol across each vineyard and juice combination when AC fining was employed, compared to their respective controls. Moreover, it was also demonstrated that juice origin (vineyard and fraction) was of a high priority when determining the aroma compound content of the experimental wines. Sensory analysis showed that the panel indicated lower counts of the aroma attribute Green vegetables for the Awatere valley wines which had been fined using AC, compared to the respective control wines. Following on from this experiment, another trial using excessive amounts of juice fining was conceived to provide information regarding part batch fining, a strategy used by some winemakers. Wairau valley press fraction juice was fined using AC, G, and PVPP at rates of 5, 6, and 8 g/L, respectively. Again, a significant (p

Author: Jokie Bakker
Publisher: John Wiley & Sons
ISBN: 1444346008
Category : Technology & Engineering
Languages : en
Pages : 453

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Book Description
Wine Flavour Chemistry brings together a vast wealth of information describing components of wine, their underlying chemistry and their possible role in the taste, smell and overall perception. It includes both table wines and fortified wines, such as Sherry, Port and the newly added Madeira, as well as other special wines. This fully revised and updated edition includes new information also on retsina wines, rosés, organic and reduced alcohol wines, and has been expanded with coverage of the latest research. Both EU and non-EU countries are referred to, making this book a truly global reference for academics and enologists worldwide. Wine Flavour Chemistry is essential reading for all those involved in commercial wine making, whether in production, trade or research. The book is of great use and interest to all enologists, and to food and beverage scientists and technologists working in commerce and academia. Upper level students and teachers on enology courses will need to read this book: wherever food and beverage science, technology and chemistry are taught, libraries should have multiple copies of this important book.